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Substances addiction is one of the important factors that deeply affect human health.At present, there is still lack of effective treatment drugs in the clinic.Exploring mechanisms of substances addiction, finding new therapeutic targets and developing effective therapeutic drugs are important issues to be solved.Hyperpolarization-activated cyclic nucleotide gated cation channels (HCN channels) participate in many advanced brain activities and are closely related to the occurrence and progression of various brain diseases.Among them, the researches on the role and mechanism of HCN channels in substances addiction are gradually gaining attention.Reviewing the researches regarding substances addiction, abnormal function and abnormal expression of HCN channels were observed in many brain regions under the condition of psychoactive substances addiction.However, it has not yet been able to fully understand the mechanism and the behavioral consequences of this change.Therefore, we review the neurobiological mechanisms of HCN channels in substances addiction induced by opioids, cocaine, cannabis, amphetamines, alcohol and tobacco, in order to provide new ideas for the mechanism researches and treatment of substance addiction.
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Hyperpolarization activated cyclic nucleotide-gated cation (HCN) channels are involved in neuronal rhythm regulation, synaptic activity, membrane resistance and dendritic integration due to their voltage-gated physiological properties. Recent studies have shown that HCN channels play an important role in central nervous system diseases, such as temporal lobe epilepsy, neuropathic pain, learning and memory disorder, substance abuse addiction and other related diseases. In this paper, we summarize the research progress of HCN channels in central nervous system diseases in recent years.
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Aim To research the effects of total flavones of rhododendra(TFR)on transient receptor potential vanilloid receptor 4(TRPV4)in cerebral basilar arteries(CBA)of rats subjected to ischemia/reperfusion(IR)injury.Methods The model of total brain IR was established by four-artery occlusion(4-VO)method in rats.Arterial pressure perfusion and cell membrane potential recording methods were used for surveying the dilatation and hyperpolarization of TFR and ruthenium red(RR,an inhibitor of TRPV4)in the KCl-preconstricted CBA ex vivo in rats subjected to IR.Quantitative real-time polymerase chain reaction(qRT-PCR)and Western blot were utilized to investigate the TRPV4 mRNA and protein expressions of TFR and RR in cerebrovascular endothelial cells of CBA in vivo in rats subjected to IR.Results 11～2 700 mg·L-1 TFR significantly induced concentration-dependent hyperpolarization and dilatation in the KCl-preconstricted CBA in rats subjected to IR.TFR still produced degenerative hyperpolarization and dilatation by removal of endothelium in CBA,which was remarkably attenuated as compared with endothelium-intact group(P<0.01).After removal of NO and PGI2 vasodilatation,TFR obviously elicited the hyperpolarization and dilatation that were further decreased by RR(an inhibitor of TRPV4)in IR CBAs.TFR pretreatment apparently increased the level of TRPV4 mRNA and protein expressions in IR CBAs.These effects were restrained by RR,an inhibitor of TRPV4.Conclusions TFR could mediate endothelium-dependent and endothelium-independent effects.The endothelium-derived dilatation may be related to the increase of endothelium activity and endothelium-derived hyperpolarizing factor(EDHF)generation and release that have been promoted by TFR,and secondarily activating TRPV4,which results in Ca2+ inflow and subsequent hyperpolarization of vascular smooth muscle cell membrane and vasorelaxation.
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Objective To explore the effect of dronedaronel on hyperpolarization-activated cyclic-nucleotide-gated(HCN) channel expression by detecting the change of HCN channel mRNA and protein level before and after giving dronedarone in neonatal rat ventricular myocytes.Methods Neonatal rat ventricular myocytes were separated and digested by type Ⅱ collagenase,and then single ventricular myocytes were collected through differential sticking wall separation method.According to the concentrations (0.1,0.5,1.0,5.0,10.0,20.0 μmol/L of dronedaronel for treating myocytes for 48 h) and time(10 μmol/L of dronedaronel for treating myocytes for 1,6,12,24,48 h)the gradient grouping was conducted.The levels of HCN2 and HCN4 channel mRNA and protein level were determined by real-time PCR and Western blot.Results The HCN2 mRNA and HCN4 mRNA expression levels in concentration gradient group and time gradient group were lower than those in the control group(P＜0.05);compared with the control group,the protein level in the 10 umol/L dronedaronel treatment for 12 h group was significantly down-regulated(P＜ 0.01).Conclusion Dronedaronel could inhibit the expression of HCN2/HCN4 channel mRNA and protein,moreover its action shows the concentration dependency and reaches the maximum at 12 h after medication.
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Hyperpolarization-activated and cyclic nucleotide-gated(HCN)channels which are distributed in a variety of tissues including excitable cells such as heart cells and different neurons have important functions in the control of heart rate and neuronal excitability. Unlike the typical potassium channels and sodium channels,HCN channels can evoke inward currents while the membrane potential is hyper-polarized. Some studies have discovered that HCN channels were important for the nervous system, due to their special electrophysiological features and regulatory effects on the cellular membrane excit-ability.HCN channels are modulated by such factors such as extracellular molecules and intracellular sig-naling cascades, which make their functions quite special in the brain. Given their role, HCN channels seem to be promising targets for specific brain disease as well as chronic pain.In this review,we focus on the roles and functions of HCN channels with their complex modulator factors and neural activity.
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[ ABSTRACT] Rebound depolarization is a special phenomenon of the neurons which generates action potential fol-lowed by a hyperpolarization stimulation.It can be recorded in many kinds of neurons and is the intrinsic membrane charac-teristic of them.Rebound depolarization plays an important role in regulating the firing pattern, rhythmic activity and sy-naptic plasticity of neurons.This review focuses on the basic characteristics, the function and mechanism of the rebound depolarization in physiological and pathological conditions, which provides reference for the clinical treatment of rebound depolarization-related diseases.
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OBJECTIVE: To investigate the dilatation and mechanism of hyperoside (Hyp) in middle cerebral arteries (MCA) of rats subjected to cerebral ischemia reperfusion (CIR). METHODS: Rat isolated MCA segments were used for surveying vasomotoricity in a pressurized chamber. Transmembrane potential was recorded by using glass microelectrodes to evaluate MCA vascular smooth muscle cell hyperpolarization. (1×10-6-1×10-4) mol·L-1 Hyp was used to investigate the effects on vasodilatation and hyperpolariza-tion in MCA of rats subjected to CIR. And the effects of nitric oxide synthase inhibitor (N-nitro-L-arginine-methyl-ester, L-NAME, 3×10-5 mol·L-1) or L-NAME plus prostaglandin I2 synthetase inhibitor (indomethacin, Indo, 1×10-5 mol·L-1) on vasorelaxation and hyperpolarization induced by Hyp were observed, respectively. Auto ELISA Detector and nitrate reductase methods were utilized to detect the H2 S and NO content in the cerebrum of rats. RESULTS: Hyp remarkably induced dose-dependent vasodilatation and hyperpolarization in 1×10-7 mol·L-1 U46619-preconstricted MCA of CIR rats. Hyp-mediated effects were notably attenuated after removal of endothelium in CIR MCA as compared with endothelium-intact group (P-5 mol·L-1) plus Indo (1×10-5 mol·L-1), the vasodilatation and hyperpolarization evoked by Hyp were significantly attenuated in sham operation group and CIR MCAs. Compared with the residual effects in sham vessels, those of CIR MCAs were remarkably potentiated (P-3 mol·L-1), an inhibitor of Ca2+-activated potassium channel, or PPG (1×10-4 mol·L-1), an inhibitor of the endogenous H2S synthese-CSE could markedly restrain Hyp-induced non-NO and non-PGP relaxation and hyperpolarization in sham and CIR vessels. As compared with CIR group, pretreatment with Hyp increased the H2S contents while decreased the NO contents. CONCLUSION: Hyp has the potential to evoke endothelium-dependent and endothelium-inde pendent effects in CIR MCAs. In these responses to Hyp, NO-mediated response is downregulated while endothelium-derived hyperpolarizing factor (EDHF) is upregulated, ie, endogenous H2S, is upregulated. Hyp can also protect the brain against cerebral ischemia injury by promoting H2S contents and decreasing NO contents of brain tissues.
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Objective T o investigate the expression of hyperpolarization-activated cyclic nucleotide-gated cation channel 4 (H C N 4) and connexin43 (C x43) in the sinoatrial node of electric shock death. Meth-ods As experim ental group, 34 cases of electric shock death who had definite current m ark evidence were selected from pathology departm ent of X uzhou M edical C ollege from 2010 to 2013. As the control group, 20 cases of fatal severe craniocerebral injury in traffic accidents were chosen. T he expressions of H C N 4 and C x43 in the sinoatrial node were observed by im m unohistochem ical technology. Results H C N 4 positive cells expressed in the cell m em brane and cytoplasm of the sinoatrial node. C x43 positive cells expressed in the cell m em brane and cytoplasm of T cells and m yocardial cells. T he expression of H C N 4 was significantly higher than that of the control group (P<0.05) and the expression of C x43 was signifi-cantly lower than that of the control group (P<0.05). Conclusion T he changes of H C N 4 and C x43 ex-pressions in the sinoatrial node illustrate electric shock death m ight be related to the abnorm alities of cardiac electrophysiology and conduction.
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BACKGROUND: Moderate and severe hypothermia with cardiopulmonary bypass during aortic surgery can cause some complications such as endothelial cell dysfunction or coagulation disorders. This study found out the difference of vascular reactivity by phenylephrine in moderate and severe hypothermia. METHODS: Preserved aortic endothelium by excised rat thoracic aorta was sectioned, and then down the temperature rapidly to 25degrees C by 15 minutes at 38degrees C and then the vascular tension was measured. The vascular tension was also measured in rewarming at 25degrees C for temperatures up to 38degrees C. To investigate the mechanism of the changes in vascular tension on hypothermia, NG-nitro-L-arginine methyl esther (L-NAME) and indomethacin administered 30 minutes before the phenylephrine administration. And to find out the hypothermic effect can persist after rewarming, endothelium intact vessel and endothelium denuded vessel exposed to hypothermia. The bradykinin dose-response curve was obtained for ascertainment whether endothelium-dependent hyperpolarization factor involves decreasing the phenylnephrine vascular reactivity on hypothermia. RESULTS: Fifteen minutes of the moderate hypothermia blocked the maximum contractile response of phenylephrine about 95%. The vasorelaxation induced by hypothermia was significantly reduced with L-NAME and indomethacin administration together. There was a significant decreasing in phenylephrine susceptibility and maximum contractility after 2 hours rewarming from moderate and severe hypothermia in the endothelium intact vessel compared with contrast group. CONCLUSION: The vasoplegic syndrome after cardiac surgery might be caused by hypothermia when considering the vascular reactivity to phenylephrine was decreased in the endothelium-dependent mechanism.
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Animals , Rats , Aorta , Aorta, Thoracic , Biological Factors , Bradykinin , Cardiopulmonary Bypass , Endothelial Cells , Endothelium , Epoprostenol , Hypothermia , Indomethacin , NG-Nitroarginine Methyl Ester , Nitric Oxide , Nitroarginine , Phenylephrine , Rewarming , Thoracic Surgery , Vasodilation , VasoplegiaABSTRACT
In this study, we determined mode of action of a novel carbamoyloxy arylalkanoyl arylpiperazine compound (SKL-NP) on hyperpolarization-activated cyclic nucleotide-gated (HCN) channel currents (Ih) that plays important roles in neuropathic pain. In small or medium-sized dorsal root ganglion (DRG) neurons (<40 microm in diameter) exhibiting tonic firing and prominent Ih, SKL-NP inhibited Ih and spike firings in a concentration dependent manner (IC50=7.85 microM). SKL-NP-induced inhibition of Ih was blocked by pretreatment of pertussis toxin (PTX) and N-ethylmaleimide (NEM) as well as 8-Br-cAMP, a membrane permeable cAMP analogue. These results suggest that SKL-NP modulates Ih in indirect manner by the activation of a Gi-protein coupled receptor that decreases intracellular cAMP concentration. Taken together, SKL-NP has the inhibitory effect on HCN channel currents (I h) in DRG neurons of rats.
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Animals , Rats , Diagnosis-Related Groups , Ethylmaleimide , Fires , Ganglia, Spinal , Membranes , Neuralgia , Neurons , Pertussis Toxin , Spinal Nerve RootsABSTRACT
Capsaicin, the pungent ingredient in hot pepper, activates nociceptors to produce pain and inflammation. However, prolonged exposures of capsaicin will cause desensitization to nociceptive stimuli. Hyperpolarization-activated cation currents (Ih) contribute to the maintenance of the resting membrane potential and excitability of neurons. In the cultured dorsal root ganglion (DRG) neurons, we investigated mechanisms underlying capsaicin-mediated modulation of Ih using patch clamp recordings. Capsaicin (1 microM) inhibited Ih only in the capsaicin-sensitive neurons. The capsaicin-induced inhibition of Ih was prevented by preexposing the TRPV1 antagonist, capsazepine (CPZ). Capsaicin-induced inhibition of Ih was dose dependent (IC50= 0.68 microM) and partially abolished by intracellular BAPTA and cyclosporin A, specific calcineurin inhibitor. In summary, the inhibitory effects of capsaicin on Ih are mediated by activation of TRPV1 and Ca(2+)-triggered cellular responses. Analgesic effects of capsaicin have been thought to be related to desensitization of nociceptive neurons due to depletion of pain-related substances. In addition, capsaicin-induced inhibition of Ih is likely to be important in understanding the analgesic mechanism of capsaicin.
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Animals , Rats , Calcineurin , Capsaicin , Cyclosporine , Egtazic Acid , Ganglia, Spinal , Inflammation , Membrane Potentials , Neurons , Nociceptors , Spinal Nerve RootsABSTRACT
Objective: To transplant the autologous mesenchymal stem cells (MSCs) carrying human hyperpolarization activated cyclic nucleoside gated channel 2 (hHCN2) gene into the His-bundle in porcine model of complete heart block (CHB), so as to assess the possibility of establishing autologous biological pacing. Methods: We constructed the recombinant adenovirus containing hHCN2 gene to transfect the porcine MSCs. After autotransplantation into the Hie-bundle in CHB model, the genetically-altered MSCs were tested for their ability to provide a stable and catecholamine-responsive heart rhythm. Histological and immunofluorescence analyses were also performed for the myocardium of the injection site. Results: Recombinant adenovirus pAd. hHCN2 was successfully constructed. Porcine MSCs were transfected by the adenovirus. After autotransplantation, transgenic MSCs significantly enhanced the heart rates in porcine CHB model compared with the control group (P < 0.01), and the cardiac rhythms in the transgenic MSC group were catecholamine responsive. Tissues obtained from the transplanted heart sites showed that the MSCs survived in the myocardium and overexpressed hHCN2 protein. Conclusion: Transplantation of autologous genetically-altered MSCs into the His-bundle in porcine CHB model can serve as a short-term catecholamine-responsive biological pacemaker.
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Objective: To study the effect of endothelium-derived hyperpolarizing factor (EDHF)-mediated responses of relaxation and hyperpolarization of vascular smooth muscle cell (VSMC) of rat cerebral basilar artery (CBA) subjected to cerebral ischemia/reperfusion (I/R) to total flavones in rhododendra (TFR). Methods: The model of global cerebral I/R in rats was made by 4-vessel occlusion (4-VO). The vasodilation and resting membrane potential (RMP) of VSMC of rat CBA were detected in vitro. Results: In the presence of 3×10-5 mol/L Nω-nitro-L-arginine-methyl-ester (L-NAME, an inhibitor of nitric oxide synthase) and 1×10-5 mol/L Indomethacin (Indo, an inhibitor of PGI2 synthesis), the global cerebral I/R markedly enhanced 1×10-7-1×10-5 mol/L acetylcholine (Ach)-elicited relaxation and hyperpolarization of RMP of VSMC in rat CBA. In the presence of L-NAME and Indo, 11-2 700 mg/L TFR induced significant and dose-dependent hyperpolarization of RMP of VSMC and relaxation of rat CBA subjected to global cerebral I/R. The hyperpolarization and relaxation were obviously inhibited by tetraethylammonium (an inhibitor IKCa at 1 mmol/L) and 1×10-4 mol/L dl-propargylglycine (PPG), an inhibitor of endogenous hydrogen sulfide (H2S) synthase. Conclusion: Global cerebral I/R could enhance the non-NO-non-PGI2-mediated responses of hyperpolarization and vasorelaxation in rat CAB. In rat CAB subjected to global cerebral I/R, TFR could significantly induce this non-NO-non-PGI2 hyperpolarization and relaxation, the so-called EDHF response that might be mediated by endogenous H2S.
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The possibility of rats mesenchymal stem cells (MSCs) modified with murine hyperpolarization-activated cyclic nucleotide-gated 2 (mHCN2) gene as biological pacemakers in vitro was studied.The cultured MSCs were transfected with pIRES2-EGFP plasmid carrying enhanced green fluorescent protein (EGFP) gene and mHCN2 gene.The identification using restriction enzyme and sequencing indicated that the mHCN2 gene was inserted to the pIRES2-EGFP.Green fluorescence could be seen in MSCs after transfection for 24-48 h.The expression of mHCN2 mRNA and protein in the transfected cells was detected by RT-PCR and Western blot,and the quantity of mHCN2 mRNA and protein expression in transfected MSCs was 5.31 times and 7.55 times higher than that of the non-transfected MSCs respectively (P＜0.05,P＜0.05).IHCN2 was recorded by whole-cell patch clamp method.The effect of Cs+,a specific blocker of pacemaker current,was measured after perfusion by patch clamp.The results of inward current indicated that there was no inward current recording in non-transfected MSCs and a large voltage-dependent inward and Cs+-sensitive current activated on hyperpolarizations presented in the transfected MSCs.IHCN2 was fully activated around -140 mV with an activation threshold of-60 mV.The midpoint (V50) was -95.1±0.9 mV (n=9).The study demonstrates that mHCN2 mRNA and protein can be expressed and the currents of HCN2 channels can be detected in genetically modified MSCs.The gene-modified MSCs present a novel method for pacemaker genes into the heart or other electrical syncytia.
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The profile of membrane currents was investigated in differentiated neuronal cells derived from human neural stem cells (hNSCs) that were obtained from aborted fetal cortex. Whole-cell voltage clamp recording revealed at least 4 different currents: a tetrodotoxin (TTX)-sensitive Na+ current, a hyperpolarization-activated inward current, and A-type and delayed rectifier-type K+ outward currents. Both types of K+ outward currents were blocked by either 5 mM tetraethylammonium (TEA) or 5 mM 4-aminopyridine (4-AP). The hyperpolarization-activated current resembled the classical K+ inward current in that it exhibited a voltage-dependent block in the presence of external Ba2+ (30micrometer) or Cs+ (3micrometer). However, the reversal potentials did not match well with the predicted K+ equilibrium potentials, suggesting that it was not a classical K+ inward rectifier current. The other Na+ inward current resembled the classical Na+ current observed in pharmacological studies. The expression of these channels may contribute to generation and repolarization of action potential and might be regarded as functional markers for hNSCs-derived neurons.
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Humans , 4-Aminopyridine , Action Potentials , Membranes , Neural Stem Cells , Neurons , Tetraethylammonium , TetrodotoxinABSTRACT
Objective To study the effect of ivabradine on hyperpolarization activated cation current in canine pulmonary vein(PY) sleeve cardiomyocytes with atrial fibrillation.Methods Dissociation of PVs yielded single cardiomyocytes from a Landengorff column without or with pacemaker activity from long-term rapidly atrial pacing (RAP) canines.If current was measured with the whole-cell patch-clamp technique.Results Compared with the control group,the rapidly atrial pacing canine PV cardiomyocytes had spontaneous diastolic depolarization and had larger If densities.Ivabradine (Iva,1 μM),a selective inhibitor of the If current,markedly reduced If currents in the RAP from -2.66±0.4 pA/pF to -1.58±0.1 pA/pF at the test potential of-120 mV (P＜0.01,n=12).Inhibition effect of Iva of If current showed concentration-dependent range from 0.1 to 10.0μM,with IC50 of 2.2 μ M ( 1.8-2.9 μM,95% CL).Furthermore,V1/ of steady-state activated curve was shifted from -84.3±4.9 mV to -106.9±3.4 mV and k value of steady-state activated curve was changed from 12.1+2.6 mV to 9.9±3.4 mV by the application of.1.0 μM Iva ( P＜0.01,n=12).Conclusions Our study revealed that Ivarbadine may significantly decrease If of rapidly atrial pacing pulmonary vein sleeve ceUs with atrial fibdllation.(J Geriatr Cardiol 2008;5:39-42)
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El dolor es un signo de enfermedad y un motivo frecuente de consulta; se clasifica en agudo o crónico, nociceptivo o neuropático, y según la velocidad de conducción en rápido o lento. Los estímulos causantes del dolor son detectados por receptores nociceptores; los cuales son identificados como fibras C y fibras Aδ. El proceso neural de la transmisiσn del dolor comprende: La transducciσn; es el proceso por el cual el estνmulo nociceptivo es convertido en seρal elιctrica en los nociceptores. La transmisiσn; es el proceso por el cual los estímulos nociceptivos son referidos al asta dorsal de la medula espinal, donde se liberan los neurotransmisores del dolor: Glutamato, sustancia P, péptido relacionado al gen de la calcitonina. Seguidamente el estímulo cruza al lado contralateral de la medula espinal y viaja en el haz espinotálamico hasta el tálamo y luego a la corteza cerebral. La modulación; es el proceso por el cual la señal nociceptiva en el asta dorsal de la medula puede ser inhibida y modificada para los centros superiores del dolor. Los opiodes endógenos y exógenos dan lugar a un bloqueo indirecto de los canales de calcio y apertura de los canales de potasio, con hiperpolarización celular e inhibición de la liberación de mediadores del dolor. La activación del sistema neural descendente da lugar a la liberación de b endorfinas, encefalinas, dinorfinas; que alivian el dolor.
Pain is a sign of illness and a common complain that bring patients to a health care facility. It is classified in acute or chronic pain, nociceptive or neuropathic, and according to conduction velocity, fast or slowly. C and Aδ- fibers respond to stimuli and produce the experience of pain, this defines them as nociceptors. Central pathways of pain include: nociceptors respond to stimuli and produce the experience of pain when they are electrically stimulated (Transduction); axons of nociceptors enter the spinal cord via the dorsal root, where Glutamate are Substance P are released, spinal neurons send their axons to the contralateral thalamus (Transmission); the perceived intensity of pain can be modulated by brain circuits (Modulation). Pain inhibition is achieved by calcium channel blockage and open potassium channel by endogenous and exogenous opioids, due hyperpolarization of the cell and inhibition of pain mediators. b endorphins, enkephalins and dinorphins are released due to activation of neural descending pathway causing pain relief.
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Aim To study the effect of ZD7288 on synaptic transmission in the pathway from perforant pathway (PP) fibers to CA3 region in rat hippocampus. Methods The extracellular recording technique in vivo was used to record the CA3 region field potentials. High-performance liquid chromatography (HPLC) with fluorescence detection was applied to measure the content of amino acids in hippocampal tissues. The effect of ZD7288 and CsCl on the amplitudes of population spike (PS) in CA3 region evoked by stimulation (0.5 Hz) of the perforant pathway (PP) fibers, and the content of amino acids in hippocampal tissue were observed. Results Microinjection of ZD7288 (20, 100 and 200 nmol)and CsCl (1,5 and 10 μmol) into CA3 region decreased the population spike (PS) amplitudes in a dosedependent manner. The inhibitory effects appeared at 5 min after microinjection and lasted at least 90 min.In those rats treated with ZD7288 (100 nmol), the contents of glutamate, aspartate, glycine and GABA decreased significantly as compared to those of saline control ( all P＜0.01, except P＜0.05 for that of glycine). A similar decrease in the contents of amino acids was observed when the rats were microinjected with CsCl (5 μmol). Conclusion ZD7288 could obviously inhibit synaptic transmission in the pathway from PP fibers to CA3 region in rat hippocampus, and this action of ZD7288 may be associated with altered contents of amino acids.
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Aim To explore the modulation of Salvia miltiorrhiza on hyperpolarization-activated current (Ih) channels in dorsal root ganglion (DRG) neurons of rats and identify the mechanism of Salvia miltiorrhiza in alleviating pain and inhibiting calcium overload. Methods The effect of Salvia miltiorrhiza injection on Ih channels in DRG neurons of rats were examined by using whole-cell patch clamp technique. Results The experimental results showed that the amplitude of Ih evoked by -150 mV was (-1.06±0.18) nA. The Ih could be fitted well into the single kinetics and the time constant of activation, τ was clearly voltage-dependent with τ=(322.14±28.81) ms at -100 mV, decreasing to τ=(62.51±9.78) ms at -150 mV. The reversal potential of Ih was (-35.03±1.12) mV measured from tail currents. But no significant differences were found between the DRG neurons in the absence and presence of Salvia miltiorrhiza injection (10%, 25%, 50%) in the current amplitude, the time constant of activation and the reversal potential. The only difference between the DRG neurons in the absence and presence of Salvia miltiorrhiza injection was the half-activation potential of Ih. In control recordings the half-activation potential was (-106.07±3.59) mV. By comparison, the half-activation potentials changed to (-111.59±3.79) mV (n=31 neurons, P＜0.05), (-119.37±4.96) mV (n=31 neurons, P＜0.05) and (-121.23±3.86) mV (n=31 neurons, P＜0.05) in the presence of 10%, 25%, 50% Salvia miltiorrhiza injection, respectively. Conclusion Only the half-activation potential of Ih in the arthritic and neuropathic rat models shifted in the depolarizing direction, which increased the electrophysiological activity of Ih and made it related to peripheral hyperalgesia. The selective inhibition of Salvia miltiorrhiza on the electrophysiological activity of Ih may be one of the mechanisms underlying its analgesic effects.
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Objective To find the way of inducing the bone marrow mesynchymal stem cells(MSCs)into cardiac cells with pacemaking function in vitro.Methods Dissociate the rat MSCs and induce them with 5AZA,bFGF+EGF,HGF,SCF and lysate of the sinoatrial cells respectively.The morphological changes were observed,and the expressing of protein cTnT,connexin 43 and HCN2/4 were analyse by immunohistologic and flowcytometry techniques.The pacmaking current If were evaluted by patch clamp techniques.Results All the methods can induce the bone marrow MSCs to differentiate into cardiac cells,which expressing cardiac cell specific protein and HCN2.Cells induced by 5AZA,bFGF+EGF and SAN CMs show higher rate of HCN2 expressing(22.9%,22.3%,11%).The cells of these groups have the pacmaking current If.Conclusion Lysate of the sinoatrial cells are ideal methods of inducing the bone marrow MSCs to differentiate into cardiac cells with pacemaking function in vitro.HCN is a promising marker protein to select pacmaking cells out of the differentiated cells.